WDE is an energy-saving and emission-cutting environmental-friendly fuel i.e. it saves fuel and also reduce CO2 emission. There are a wide variety of WDE fuels available in the market. WDE has many shortcomings that need to be addressed.
1) WDE is inherently unstable—an emulsion is defined as one liquid (dispersed phase) dispersed in another liquid (continuous phase) e.g. WDE is made up of tiny water droplets (dispersed phase) dispersed in diesel (continuous phase). Since water has a higher density than diesel, gravity will cause the dispersed water droplets to descend. This, not only, occur in the fuel tank, it occur throughout the fuel supply system, from the fuel tank right through to the fuel injectors. This phenomenon compromises fuel consistency and engine performance.
2) Power loss when running on WDE. All leading WDE suppliers mention loss of engine power commensurate to its water content.
3) Viscosity of WDE at around 40 CST is significantly higher than that of pure diesel. This will adversely impact its fuel delivery rate. In other words, fuel delivery rate to the engine will be drastically reduced if no modification is done to a fuel system that is designed for diesel
4) Low speed engine instability when running on WDE.
5) The entire fuel system has to be purged of WDE before a vehicle running on WDE can resume using diesel. For instance, patent no. 03227816.0 diesel emulsion equipment mentions that an engine fitted with its invention can only run on WDE.
6) Lack of refueling facility. WDE fuels from different suppliers are incompatible with one another. Current WDE suppliers use a variety of emulsifying technologies. Emulsification formulations are like computer application software. Each proprietary formulation is unique and not compatible to one another.
7) Present emulsion fuel users are limited to city buses, boilers, ocean-going ships and power stations.
8) Present suppliers of dual-fuel equipment—WDE and diesel fuel—are incomplete solutions and unworkable. For instance, patent no. 200820089521.9 “diesel engine emulsion-fuel and diesel-fuel dual-fuel supply equipment” do not address an engine's return fuel. Return-fuel can contain air bubbles, emulsion fuel, and diesel or a combination of all three. This issue has to be addressed as it can compromise the fuel quality of whichever fuel tank it returns to. The said invention is essentially unworkable. The addition of a third tank for return fuel will face the principle of “communicating vessels” i.e. liquid levels of all communicating vessels will be the same.
9) Prior art of supplying ready-mix WDE fuel faces issues such as high product cost; fluctuating diesel price beyond the control of the WDE fuel producer will make loss-prevention difficult; production of WDE will need the approval of state regulatory bodies.
10) Engine running on WDE is difficult to start.